I think you've posted here before and have probably been told what the risks of HIV transmission are. It is sexually transmitted. Right? So, smelling and touching do not qualify as risks. The only way that people get HIV is from unprotected vaginal or anal intercourse (penetrating) and sharing IV drug needles. Air and saliva inactivate the virus. So, smelling underwear or touching vaginal fluid with your mouth or hand is not a risk for HIV.
I second GR. Your panty fetish can't provide a scope for HIV transmission.